1) An upright bar, especially in a window. In early references they were often made of wood but some were of iron as early as 1472-3 (OED).
1335 Stanciones vero erunt novem enchiarum, York
1433 iij balkes, iiij stanzones, vij bandclogs, York
1454-5 et j quart’ meremii in burdis, stauns, York
1490 De viij bordes cum j stannshon stantibus inter coquinam et lez bowyltyng-hows, York
1637 tenn windowe stanchions of iron, Liversedge
1726 the persons which stole the goods did take out a window stanchion in order to get into her house and went out at the back door, Bretton
1779 For Iron Stanshals for the church, Kirby Underdale.